Stepper motors such as described in U.S. Pat. No. 5,369,324 entitled “Electrical Stepper Motor” often contain power transistors within the motor control circuit. Since the power transistors generate heat upon operation of the associated stepper motor, heat sinks are required to prevent the stepper motor and motor control circuit from overheating.
In some electric circuits containing power transistors, a heat sink is attached to the power transistor by means of a spring clip arrangement to insure close contact between the power transistor and the heat sink for efficient heat transfer away from the power transistor, per se. One example of a spring clip arrangement is found in U.S. Pat. No. 5,671,118 entitled “Heat Sink and Retainer for Electronic Integrated Circuits”
When the power transistor is arranged within an electrical enclosure, a heat sink in the form of a metal support plate is arranged on the bottom of the enclosure to allow air flow access to the heat sink. One example of such an arrangement is found in U.S. Pat. No. 6,249,435 entitled “Thermally Efficient Motor Controller Assembly”.
The attachment of the power transistors to the heat sink within an electrical enclosure is complicated when the heat sink is part of the enclosure, per se.
One purpose of the instant invention is to provide an electrical stepper motor enclosure whereby the power transistors employed within the motor control circuit automatically become spring-loaded into contact with a heat sink, which serves as the power transistor enclosure, upon attachment of the enclosure to the stepper motor support housing.